Abstract
The focus of this study is the behaviour of the lift-off point of intersection (LOI) under various test conditions: lift-off, thickness and conductivity of metallic layers with and without a ferromagnetic substrate. The pulsed eddy current (PEC) signal response is analyzed and a lift-off independent method to measure the thickness of conductive layers over ferromagnetic substrates is presented. This approach is tested by scanning specimens with varying lift-off and conductive layer thickness. The test articles have different substrate permeabilities, but identical lift-off and conductive layer conditions. The results demonstrate that the LOI feature can be used to measure the thickness of conductive layers over ferromagnetic substrates.